package com.ktgj.train.utils;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.security.SecureRandom;

public class DESUtils {

    private static final String DES = "DES";

    private static final String key = "u0FKpzhZa1x1DeWn";

    /**
     */
    public static String decrypt(String data) {
        try {
            if (data == null)
                return null;
            BASE64Decoder decoder = new BASE64Decoder();
            byte[] buf = decoder.decodeBuffer(data);
            byte[] bt = decrypt(buf, key.getBytes());
            return new String(bt, "UTF-8");
        } catch (Exception e) {
            return data;
        }
    }

    /**
     */
    public static String encrypt(String data) throws Exception {
        return new BASE64Encoder().encode(encrypt(data.getBytes("UTF-8"), key.getBytes()));
    }

    /**
     * 加密
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
        //生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();
        //从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);
        //创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);
        //Cipher对象实际完成加密操作
        Cipher cipher = Cipher.getInstance(DES);
        //用密钥初始化Cipher对象
        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
        //返回
        return cipher.doFinal(data);
    }

    /**
     * 解密
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
        //生成一个可信任的随机数源
        SecureRandom sr = new SecureRandom();
        //从原始密钥数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);
        //创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);
        //Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance(DES);
        //用密钥初始化Cipher对象
        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
        //返回
        return cipher.doFinal(data);
    }
}
